1. Field of the Invention
This invention relates to floor panels, as well as to floor coverings composed of such floor panels.
2. Related Art
More particularly, the invention relates to floor panels intended for forming a floating floor covering and which, during installation, may be coupled to each other at their edges by means of mechanical coupling parts, whether or not made in one piece with the floor panel, which provide for a mutual locking of the floor panels in horizontal as well as in vertical direction, for example, such as described in the International Patent Applications WO 94/26999, WO 97/47834, WO 01/98603 and WO 01/96688.
The floating installation of floor panels allows a free expansion or shrinkage of the floor covering with a changing environmental climate. In order to allow for expansion, the floor covering is installed up to a certain distance, in the order of magnitude of 1 centimeter, from the wall of a room. The space thus kept free at the edge of the room, currently called expansion gap, usually is covered by a finishing profile or end profile. With the existing floating floor coverings, it is recommended to apply such expansion gaps in the floor surface, too, when the surface of the floor covering becomes too large and, for example, exceeds the distance of 12 meters in longitudinal or transverse directions. For covering an expansion gap in the surface of the floor covering also a finishing profile, more particularly an expansion profile, is applied. Said end profiles and expansion profiles are described, for example, in WO 2006/074824. Said finishing profiles, and then in particular said expansion profiles situated in the surface of the floor covering, are experienced by the user as disturbing, as they interrupt the floor surface by protruding above the floor surface and usually have other dimensions than the floor panels themselves. There is a desire to avoid or to restrict the application of such profiles, as well as there is the desire to limit the dimensions of the required expansion gap.
With a changing environmental climate, floatingly installed floor coverings moreover show further disadvantages in the case that heavy loads, such as furniture, are placed upon the floor surface. Such loads in fact may hinder or prevent the free expansion and/or shrinkage of the floor. Such hindrance or prevention may result in the unlocking of floor panels in the floor covering when shrinking and in the warping of the floor covering when expanding.
From the state of the art, several suggestions are known in order to fully or partially avoid the problems outlined above and/or to fully or partially meet the desires outlined above.
The solutions presented in WO 94/26999, WO 2005/068747 and WO 2006/066639 respectively relate to floor panels which can be coupled at their sides by means of mechanical coupling parts provided with a certain built-in play. This play can provide for a mutual freedom of movement between the coupled floor panels. Another example of such coupling is known from WO 2004/081316. In this latter document, the space of the play, however, is filled with a sealing material having no mechanical strength. However, in the suggestions in each of the herein-mentioned international applications, there is the risk that floor panels initially are installed in a position in which the upper edges of the floor panels concerned already are touching, such that, in case of a possible expansion, they can not move farther towards each other and the suggested solution may solely be active in a situation where the floor panels move away from each other, such as during shrinking. The reverse is possible, too, namely that the floor panels are installed in an initial mutual position in which they can not move farther away from each other, for instance, when shrinking.
From document JP 8-109734, it is known to implement mechanical coupling parts such that the floor panels initially always are installed such that there is an intermediate space at the height of the upper edges of the coupled floor panels, between the respective coupled sides. With the floor panels known from this document, it is always possible to counterbalance an expansion of the floor panels to a certain extent, or, in other words, it is always possible to allow a movement of the coupled floor panels towards each other to a certain extent. However, with the solution proposed in this document, it is impossible to counterbalance shrinkage of the floor panels.